Author J.K. Rowling’s first novel, Harry Potter and the Philosopher’s Stone, was published in Britain on June 26, 1997.

Since then, it has sold more than 450 million copies worldwide and has been translated into 79 languages. The books’ magical world has inspired multiple films, spinoffs, memorabilia and amusement park attractions. The White Elephant Cafe, the Edinburgh spot where Rowling wrote the first book, has become an international tourist destination.

“20 years ago today a world that I had lived in alone was suddenly open to others,” Rowling tweeted. “It’s been wonderful. Thank you.”

Rowling’s publisher, Bloomsbury, will release four new editions of the book, one for each house at Hogwarts School of Witchcraft & Wizardry, in honor of the anniversary.

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